- DenTron MLA-2500 FAN Replacement and modification


The new FAN in place

- The modification -
The MLA-2500 original fan is quit noicy, so i decided to trye to do something about this problem. In the Cooling mode By LX2KL i got the general lineout. Here is a description of how i made the mod. I use a 'PAPST TYPE 4650N' fan for the mod. The new fan is for 220V and the original is for 110 volt. so i also had to make som mods for the speed reduction resistor 'R9' and also for the supply voltage for the fan.


The old fan is removed

The rubber vibration bushings is originally spare parts for a chain saw, i had to drill the original screw holes a little bigger and then i use washers inside.


Fan fitting detail

I made an frame of 0,5mm aluminum plate to make a fitting for the air to flow into the original fan hole.


Fan fitting detail in place


Resistor replacement

Due to the different voltage, and also to get the fan to run i lower speed when not transmitting i also replaced the resistor 'R9'. The original resistor is 380ohm 25W, i replaced it with 1.5k ohm.

Addisional voltage correction
The fan i use is for 220-240V DC, so i also needed to correct the voltage for the fan, this is easily done by moving one of the fan wires coing from the primary side of the transformer. The photos is illustrating this.


Original wire position for 110V


Modified wire position for 220V

- Technical data -

FAN FACTORY SPECIFICATIONS
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Typ    Lager   m3/h   dBA   °C             v/min  Pa  VA
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4650N  Glid-   160    40    -10 till +55   2650   80  19